In some processes for forming carton blanks, apparatus is used to laminate together a continuous strip of a relatively rigid material and a continuous strip of a relatively flexible material. Under some operating conditions, there is a tendency for the laminated materials to curl. The operating conditions relate to the type of adhesive being used and the manner in which the continuous strip of a relatively rigid material and the continuous strip of a relatively flexible material are fed into the nip between the laminating rolls. In the curled product, an arcuate shape extending in the machine direction is formed between the ends of the carton blank wherein the inner surface of the arcuate shape comprises the relatively flexible material. Under these conditions, the adhesive being used is a liquid adhesive that is tacky at room temperatures which under desirable operating conditions is between 60.degree. F. and 80.degree. F. but could be as high as 110.degree. F. However, as the temperature approaches 110.degree. F., the liquid adhesive does not perform as well. Also, under these conditions, the continuous strip of a relatively rigid material and the continuous strip of a relatively flexible material are fed from opposite sides of a plane tangent to the laminating rolls at the nip therebetween or at least one of the continuous strips is in the plane tangent to the laminating rolls at the nip therebetween. In most instances, the amount of curl is slight but can interfere with further processing of the carton blanks. Many types of liquid adhesives were tried in an effort to eliminate the curl. Therefore, it is desirable to eliminate or at least to minimize the amount of curl.
In conventional apparatus for forming carton blanks, a laminate of desired materials is made and then appropriate cut lines and fold lines are formed in the laminate. Also, the individual carton blanks may be formed at the same time or formed in a separate operation.
In U.S. Pat. No. 3,942,708 there is disclosed a process wherein individual carton blanks of a relatively rigid material are fed onto a moving continuous strip of a relatively flexible material. It is stated that an adhesive material is applied either on the continuous strip of a relatively flexible material or on the individual carton blanks. It is further stated that the individual carton blanks are formed in a separate operation. There is no illustration or explanation of any apparatus for feeding the individual punched carton blanks onto the continuous strip of a relatively flexible material. After being deposited on the continuous strip of a relatively flexible material, each individual carton blank and the continuous strip of a relatively flexible material are pressed together by suitable apparatus.